Initial development and preliminary psychometric properties of the Prodromal Inventory of Negative Symptoms (PINS)

Abstract

In the psychosis prodrome, sub-threshold positive symptoms are often preceded by negative symptoms. Individuals exhibiting these attenuated symptoms are primarily adolescents and young adults at clinical high-risk (CHR) for developing a psychotic disorder. In the CHR state, negative symptoms are highly predictive of the transition to diagnosable illness, making the assessment of these symptoms very important. Existing scales used to evaluate negative symptoms in this critical population are informative but have conceptual and psychometric limitations and/or were not designed according to modern conceptions delineated in the 2005 NIMH Negative Symptom Consensus Conference. The current study reports the development of the Prodromal Interview of Negative Symptoms (PINS) – a next-generation scale designed in accordance with the consensus conference recommendations. Preliminary data on the psychometric properties of the PINS is reported as part of ongoing scale development that will use a data-driven, iterative process to generate a final scale. Analysis of data from 53 CHR cases, 30 of whom were re-evaluated at 12 months, indicated that the beta version of the PINS demonstrated good internal consistency, inter-rater reliability, convergent validity, and discriminant validity. These preliminary findings provide direction for a revision of this measure, which resulted in the PINS-2, a promising new measure for the assessment of negative symptoms in CHR populations. This manuscript presents both the initial scale and resulting untested instrument, as well as a series of plans and recommendations for future development.

Introduction

Negative symptoms are a core feature of schizophrenia and predict a number of clinically important outcomes, such as recovery, subjective well-being, quality of life, and functional outcome (Fervaha et al., 2014, Foussias et al., 2014, Millan et al., 2014, Strauss et al., 2010).

The National Institute of Mental Health (NIMH) held a consensus conference in 2005 to promote progress in this area of psychopathology (Kirkpatrick et al., 2006). Among the key conclusions from this conference were: 1) there are at least 5 core domains of negative symptoms, including anhedonia (diminished intensity or frequency of pleasure), avolition (diminished initiation of and persistence in goal-directed activity), asociality (reduced frequency and/or desire for social interaction), blunted affect (diminished facial, vocal, and body expression) and alogia (reduced quantity of speech) and 2) new negative symptom rating scales are needed to assess these specific domains.

Two next-generation negative symptom rating scales resulted from the 2005 consensus conference: the Clinical Assessment Interview for Negative Symptoms (CAINS) (Horan et al., 2011, Kring et al., 2013) and the Brief Negative Symptom Scale (BNSS) (Kirkpatrick et al., 2011, Strauss et al., 2012). The CAINS and BNSS have demonstrated good psychometric properties, and factor analytic studies indicate that the five negative symptoms load onto two dimensions: motivation/pleasure (MAP) (anhedonia, avolition, asociality) and diminished expression (EXP) (blunted affect and alogia) (Horan et al., 2011, Kring et al., 2013, Strauss et al., 2012). Subsequently, the CAINS and BNSS are becoming widely used in experimental psychopathology and clinical trial studies examining the chronic phase of schizophrenia (Gur et al., 2015, Johnson et al., 2011, Wolf et al., 2014).

Despite this progress, the NIMH consensus conference did not discuss development of negative symptom scales specific to youth at clinical high-risk (CHR) for developing psychosis. The development of such scales is important, as negative symptoms play a vital role in the developmental trajectory of psychosis, predicting the transition to diagnosable psychotic disorders (Johnstone et al., 2005, Piskulic et al., 2012). In North America, negative symptoms are most commonly evaluated in CHR populations using the Structured Interview for Prodromal Syndromes (SIPS) (McGlashan et al., 2001). The SIPS is well-validated, commonly used, and has been vital to our understanding of CHR youth. However, the SIPS negative symptom items have some limitations with content validity (e.g., the social anhedonia item conflates asociality, social anxiety, and social skill, and does not evaluate pleasure specifically). Most notably, when examining the SIPS negative symptoms (social anhedonia, avolition, expression of emotion, experience of emotions and self, ideational richness, and occupational functioning), it is readily apparent that these items do not map onto the domains identified by the NIMH 2005 Consensus Conference. This is a significant issue, as it is not currently possible to assess negative symptoms in CHR youth in relation to the modern constructs delineated in the 2005 NIMH Consensus Meeting. Incorporating the CAINS or BNSS into an assessment battery for the prodromal syndrome is one potential option that has been done (Gur et al., 2015); however, these scales were developed for adults with formal psychosis already experiencing negative symptoms, and these scales may not pick up on the subtleties of newly emergent attenuated negative symptoms in CHR youth. Thus, there is still need for the development of a new negative symptom rating scale designed specifically for the prodromal phase of illness that incorporates modern conceptualizations of negative symptoms.

The current study reports the development of a new scale designed to address these limitations – the Prodromal Interview of Negative Symptoms (PINS). Preliminary psychometric properties are reported for the beta version of the PINS, which represents the first step of what will be an iterative and data-driven process to develop and validate a next-generation measure. Future efforts will include a series of multi-site psychometric studies designed to determine which items to add, modify, retain or eliminate.